1. Field of the Invention
The present invention relates to compositions and methods for treating water, and in particular, compositions containing silver and a material such as aluminum or zinc.
2. Description of the Related Art
In many situations, water is purified to remove microorganisms, such as bacteria or algae, and harmful metal ions, such as mercury, lead and copper. Water purification may be accomplished by filtration, providing water suitable for consumption or for use in recirculating systems such as swimming pools, hot tubs, spas and cooling towers. Water purification may also be accomplished by adding chemicals like chlorine or bromine. However, it has been found that not only does chlorine have an objectionable odor, but that it can also cause skin irritations and serious eye irritations to bathers in pools or spas.
Because of the objectionable physical properties of chlorine a number of alternate water treatment systems which operate without chlorine have been developed in recent years. One of the most effective types of alternative water treatment systems is a system in which silver ions are added to water to kill microorganisms therein. However, it has been found that in many cases systems of this type are only partially effective due to insufficient control of the silver ion levels, which should be maintained between about 0.01 ppm and about 0.1 ppm. Failure to maintain this ion level concentration may result in staining or health problems.
Accordingly, a water purification composition that provides better control of the silver ion levels will provide an improvement over conventional silver-containing water purification compositions by avoiding or reducing the effect of disadvantages as noted above.